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Norio Shibata

Publications and source records attributed to Norio Shibata.

15 recordsLinked to original sources
PubMed2006

Lewis acid-catalyzed enantioselective hydroxylation reactions of oxindoles and beta-keto esters using DBFOX ligand.

The first catalytic enantioselective hydroxylation reaction of both 3-aryl and 3-alkyl-2-oxindoles using the DBFOX-Zn(II) complex, leading to pharmaceutically important chiral 3-hydroxy-2-oxindoles was described. The structure of oxidant was found to play an important role to increase the enantioselectivity. The methodology has successfully applied to the highly enantioselective hydroxylation of beta-keto esters using the DBFOX-Ni(II) complex.

Catalysis↗
PubMed2006

Enhanced fluorescence resonance energy transfer immunoassay with improved sensitivity based on the Fab'-based immunoconjugates.

Fluorescence resonance energy transfer (FRET) is a powerful technique to monitor protein-protein interaction. Recently, we developed homogeneous and noncompetitive immunoassay based on the enhanced FRET by leucine zipper interaction. Here we improved the assay by establishing a general method for preparation of the Fab'-based immunoconjugate. Anti-human serum albumin Fab' numbers 11 and 13 were chemically conjugated with recombinant proteins consisting of thioredoxin, flexible linker, and green fluorescent protein color variant tethered with a leucine zipper motif. Compared with single chain antibody variable region-based fusion proteins prepared by the gene fusion method in our previous study, the resultant Fab'-based immunoconjugates accomplished an assay with nearly 10 times greater sensitivity. Furthermore, the conjugation method enabled us to apply the assay generally to measurement of another high-molecular weight antigen for which antibodies prepared for sandwich immunoassay are commercially available. Because of the facility and generality of the preparation method for the immunoconjugate, the assay is expected to be applied to many antigens that require rapid diagnosis and moderate measurement range.

Fluorescence Resonance Energy Transfer↗
PubMed2006

Fabrication of small complex-shaped optics by plasma chemical vaporization machining with a microelectrode.

We have developed plasma chemical vaporization machining by using a microelectrode for the fabrication of small complex-shaped optical surfaces. In this method, a 0.5 mm diameter pipe microelectrode, from which processing gas is drawn in, generates a small localized plasma that is scanned over a workpiece under numerical computer control to shape a desired surface. A 12 mm x 12 mm nonaxisymmetric mirror with a maximum depth of approximately 3 microm was successfully fabricated with a peak-to-valley shape accuracy of 0.04 microm in an area excluding the edges of the mirror. The average surface roughness was 0.58 nm, which is smooth enough for optical use.

Journal Article↗
PubMed2006

Lewis acid-catalyzed tri- and difluoromethylation reactions of aldehydes.

The first Lewis acid-catalyzed trifluoromethylation reactions of aldehydes with Me3SiCF3 under TiF4/DMF, Ti(O iPr)4/DMF and Cu(OAc)2/dppp/toluene conditions are described. We have successfully applied this methodology to the difluoromethylation of aldehydes using Me3SiCF2SePh, Me3SiCF2P(O)OEt2 and Me3SiCF2SPh.

Journal Article↗
PubMed2005

Cinchona alkaloid/sulfinyl chloride combinations: enantioselective sulfinylating agents of alcohols.

We report a novel approach to asymmetric sulfinylation reactions based on a cinchona alkaloid/sulfinyl chloride combination that acts as the first asymmetric sulfinylating agents of achiral alcohols. Both enantiomers of arenesulfinates are obtained with up to 99% ee. The significantly high enantioselectivity observed in this case could be explained by dynamic kinetic resolution.

Alcohols↗
PubMed2005

Urinary excretion of liver fatty acid-binding protein in health-check participants.

BACKGROUND: Messenger RNA of liver fatty acid-binding protein (L-FABP) is expressed in proximal tubules of the kidney, and a certain amount is excreted into urine. We analyzed factors relating to the urinary L-FABP excretion in health-check participants. METHODS: We measured L-FABP in the first morning urine by ELISA in 715 men and 193 women 30-79 years of age who entered a 2-day hospitalized health checkup program. In addition to the routine physical examination and laboratory tests, plasma high-sensitivity C-reactive protein (HSCRP) was assayed. RESULTS: In 150 healthy subjects, urinary L-FABP averaged 3.6 +/- 0.2 microg/g creatinine, whereas the values were significantly increased in patients with hypertension (5.2 +/- 0.4, P = 0.010), diabetes mellitus (5.5 +/- 0.5, P < 0.001), and chronic hepatitis (5.8 +/- 1.0, P = 0.022). Urinary L-FABP excretion was significantly greater in women than in men when the value was related to creatinine. In regression analysis in men, urinary L-FABP was positively correlated with fasting plasma glucose (r = 0.103, P = 0.033) and plasma HSCRP (r = 0.135, P = 0.006). CONCLUSIONS: It is suggested that renal production and urinary excretion of L-FABP are increased in situations in which arteriosclerosis is promoted, such as hypertension, diabetes mellitus, and cardiovascular inflammation.

Adult↗
PubMed2004

Chiral discrimination between thalidomide enantiomers using a solid surface with two-dimensional chirality.

Chiral discrimination between thalidomide enantiomers was achieved using the self-assembled monolayer (SAM) of an atropisomeric compound, 1,1'-binaphthalene-2,2'-dithiol (BNSH), which takes a two-dimensional chiral arrangement on gold(111) surface. Interestingly, an "all-or-none" type enantioselectivity appears; one enantiomeric form of BNSH SAM allows the adsorption of only one enantiomer of thalidomide. In addition, the response of a racemic SAM of BNSH was revealed to be one-half of that caused by pure enantiomeric SAM.

Carboxylic Acids↗
PubMed2003

Enantioselective fluorination mediated by N-fluoroammonium salts of cinchona alkaloids: first enantioselective synthesis of BMS-204352 (MaxiPost).

We have employed a cinchona alkaloid/Selectfluor-mediated enantioselective fluorination of the oxindole 2 to achieve the first enantioslective synthesis of BMS-204352 (MaxiPost, S-1), an effective opener of maxi-K channels. Fluorination occurred to produce S-1 with 84% ee using the bis-cinchona alkaloid (DHQ)(2)AQN. Recrystallization produced enantiomerically pure (>99% ee) product. Quinidine-mediated fluorination of 2 gave the (R)-antipode of 1 with 68% ee.

Catalysis↗
PubMed2002

Fabrication of optics by use of plasma chemical vaporization machining with a pipe electrode.

We figure optical surfaces by plasma chemical vaporization machining (CVM) with a pipe electrode, in which an rf plasma generated at the electrode tip under approximately atmospheric pressure moves over the surfaces. We propose a shaping method in which the movement of plasma on the surfaces can be determined. Flat and aspheric surfaces are successfully figured with the desired peak-to-valley shape accuracy of 0.1 microm. The root-mean-square roughness of the resultant surfaces is at the subnanometer level. These results confirm that the plasma CVM and the shaping method have the capability to fabricate optics with high accuracy.

Journal Article↗
PubMed2001

Synthesis of Fluorogypsetin and Fluorobrevianamide E by a Novel Fluorination-Cyclization of cyclo-L-Trp-L-AAs This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture, Japan. N.S. wishes to thank the Novartis Foundation (Japan) for the Promotion of Science for support. We thank Prof. Yoshio Takeuchi very much for generously sharing his facilities, for very kind encouragement and for giving us the opportunity to study in the field of fluorine chemistry. We also thank F-TECH INC. for a gift of FP-T300.

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Journal Article↗